A zirconia-based sintered body, that is, in particular, a tetragonal-system zirconia-based sintered body, has been applied to household articles, such as edged tools, and sports goods, such as spikes for golf shoes, because of its high strength and superior surface gloss after mirror polishing, and its applications have been expanded to decorative members, such as watch cases and accessories, high-grade building materials, mechanical members, such as various structural members, and ceramics electronic members, such as substrates and the like, of electronic parts. In order to respond to these expanding applications, there have been strong demands for colored zirconia having various colors other than conventionally-known black color.
For example, JP-A No. 62-108779 has proposed a blue-color ceramic decorative member produced by adding cobalt oxide to partially-stabilized zirconia. Here, JP-B No. 8-18868 has proposed a colored zirconia-based sintered body with high strength having a blue color, which is formed by adding Fe3O4 and TiO2 to yttria-stabilized zirconia. Moreover, U.S. Pat. No. 2,821,680 has proposed a blue-colored zirconia-based sintered body formed by adding Al2O3 and CoO to stabilized zirconia. Furthermore, JP-A No. 59-105055 has proposed a zirconia-based colored member having a light green color, which is formed by adding NiO to yttria- or calcia-stabilized zirconia. U.S. Pat. No. 2,645,443 has proposed a zirconia-based sintered body having a yellow color, which is formed by adding Al2O3 and NiO to yttria-stabilized zirconia. JP-A No. 59-174574 has proposed a partially stabilized zirconia-based sintered body, which contains alumina particles formed by solid-saluting an oxide of at least one kind of transition metal selected from Mn, Ti, Fe, V, Co, Cr and Ni, in a dispersed state, and has reported that the application of CoO produces a blue color, the application of Cr2O3 produces a light red color and the application of MnO produces a brown color.